Scenario conditions in dialogs: option if= hides choices, when moved here from stat checks; command schemas

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/Scenarios/Impls/WhenCommandStrategy.cs

@@ -0,0 +1,43 @@
+namespace Cthangover.Mods.Dialog.Scenarios
+{
+    using System.Collections.Generic;
+    using Cthangover.Core.Localization;
+    using Cthangover.Core.Scenes;
+    using Cthangover.Mods.Dialog;
+
+    /// <summary>
+    /// A conditional jump in the middle of a dialog:
+    /// <code>when "stat(cha) &gt;= 5 &amp;&amp; door == 'open'" -> :persuaded [else=refused]</code>
+    /// evaluates the shared condition language (flags, quests, stats, equipment, GDScript
+    /// conditions — everything mods registered) at the moment the line runs, and jumps to
+    /// the arrow label when it holds, to <c>else</c> when it does not (or goes on).
+    /// <para/>
+    /// It is the RPG Maker "Conditional Branch" without a new syntax: the condition is the
+    /// same text a scenario header's <c>condition:</c> takes. Several words without quotes
+    /// are joined back with spaces, so short conditions need no quotes.
+    /// </summary>
+    public class WhenCommandStrategy : IScenarioCommandStrategy, IScenarioCommandSpec
+    {
+        /// <inheritdoc />
+        public string Command => "when";
+
+        /// <inheritdoc />
+        public int MinPositional => 1;
+
+        /// <inheritdoc />
+        public IReadOnlyList<string> AllowedNamed => new[] { "else" };
+
+        /// <inheritdoc />
+        public string JumpTargetNamedKey => "else";
+
+        /// <inheritdoc />
+        public void Execute(DialogQueue dlg, List<string> positional, Dictionary<string, string> named, string arrowTarget, ILocalizationProvider locale)
+        {
+            var condition = string.Join(" ", positional);
+            named.TryGetValue("else", out var otherwise);
+            dlg.IfGoTo(() => ScenarioCondition.Evaluate(condition), Label(arrowTarget), Label(otherwise));
+        }
+
+        private static string Label(string target) => string.IsNullOrWhiteSpace(target) ? null : target.Trim().TrimStart(':');
+    }
+}

src/Scenarios/ScenarioParser.cs

@@ -103,7 +103,10 @@ namespace Cthangover.Mods.Dialog.Scenarios
 
                     if (pendingSelect.Variants == null)
                         pendingSelect.Variants = new List<SelectVariant>();
-                    pendingSelect.Variants.Add(SelectVariant.New(optText, goTo));
+                    var variant = SelectVariant.New(optText, goTo);
+                    if (named.TryGetValue("if", out var condition))
+                        variant.Condition = condition;
+                    pendingSelect.Variants.Add(variant);
                     continue;
                 }
 

src/UI/Dialog/Action/Impls/ActionSelect.cs

@@ -1,4 +1,6 @@
 using System.Collections.Generic;
+using System.Linq;
+using Cthangover.Core.Utils;
 using Cthangover.Mods.Dialog.Action;
 using Godot;
 using Cthangover.Core.UI;
@@ -35,16 +37,29 @@ namespace Cthangover.Mods.Dialog.Action.Impls
         public override WaitType WaitType { get; set; } = WaitType.WaitSelect;
 
         /// <summary>Substitutes variables in the variants and context text, then shows the answer box; the runtime stays paused until a variant is picked.</summary>
+        /// <summary>
+        /// Offers the options whose conditions hold now. When none does, the choice is
+        /// skipped and the dialog goes on with the next line, so a choice of only gated
+        /// options never leaves the player stuck.
+        /// </summary>
         public override void DoRun(DialogRuntime runtime)
         {
             var dialogBox = runtime.DialogBox;
             if (dialogBox == null)
                 return;
 
-            foreach (var variant in Variants)
+            var shown = Variants.Where(v => v.IsShown()).ToList();
+            WaitType = shown.Count == 0 ? WaitType.NoWait : WaitType.WaitSelect;
+            if (shown.Count == 0)
+            {
+                GameLogger.Log("DIALOG", "select: no option is shown (all conditions false), going on", LogLevel.Debug);
+                return;
+            }
+
+            foreach (var variant in shown)
                 variant.Text = runtime.ProcessText(variant.Text);
 
-            dialogBox.SetVariants(Variants);
+            dialogBox.SetVariants(shown);
             dialogBox.SetText(runtime.ProcessText(Text));
         }
     }

src/UI/Dialog/Action/Impls/SelectVariant.cs

@@ -23,6 +23,16 @@ namespace Cthangover.Mods.Dialog.Action.Impls
         /// <summary>Target action ID to jump to via <see cref="DialogRuntime.TryGoTo"/> when this variant is selected.</summary>
         public string GoTo { get; set; }
 
+        /// <summary>
+        /// Condition of the shared condition language (<c>option "…" if=… -> :label</c>); the
+        /// option is shown only while it holds. Null = always shown. Evaluated each time the
+        /// choice appears, so a stat, a flag or an item gained a moment ago counts.
+        /// </summary>
+        public string Condition { get; set; }
+
+        /// <summary>Whether the option is offered now.</summary>
+        public bool IsShown() => string.IsNullOrWhiteSpace(Condition) || ScenarioCondition.Evaluate(Condition);
+
         /// <summary>Generates a new unique action ID for use as a GoTo target (e.g. with <see cref="DialogQueue.Point"/>).</summary>
         public static string Point => Guid.NewGuid().ToString();